Messages in this thread | | | Date | Wed, 17 Aug 2011 23:38:18 -0700 | From | Dmitry Torokhov <> | Subject | Re: [PATCH 3/6] Input: elantech - packet checking for v2 hardware |
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On Thu, Aug 18, 2011 at 09:57:06AM +0800, JJ Ding wrote: > For v2 hardware, there is no real parity check, but we can still check > some constant bits for data integrity. > > Signed-off-by: JJ Ding <jj_ding@emc.com.tw> > --- > drivers/input/mouse/elantech.c | 26 +++++++++++++++++++++++--- > 1 files changed, 23 insertions(+), 3 deletions(-) > > diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c > index cf41f23..032181c 100644 > --- a/drivers/input/mouse/elantech.c > +++ b/drivers/input/mouse/elantech.c > @@ -376,6 +376,25 @@ static int elantech_check_parity_v1(struct psmouse *psmouse) > etd->parity[packet[3]] == p3; > } > > +static int packet_simple_check_v2(struct psmouse *psmouse) > +{ > + struct elantech_data *etd = psmouse->private; > + unsigned char *packet = psmouse->packet; > + > + if (etd->reports_pressure) > + return (packet[0] & 0x0c) == 0x04 && > + (packet[3] & 0x0f) == 0x02; > + > + if ((packet[0] & 0xc0) == 0x80) > + return (packet[0] & 0x0c) == 0x0c && > + (packet[3] & 0x0e) == 0x08; > + > + return (packet[0] & 0x3c) == 0x3c && > + (packet[1] & 0xf0) == 0x00 && > + (packet[3] & 0x3e) == 0x38 && > + (packet[4] & 0xf0) == 0x00;
Can we please spell out the assumptions under which we decide that packet is invalid?
Thanks.
-- Dmitry
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